A conventional credit card, as illustrated in FIG. 1, contains a magnetic stripe on which is encoded several tracks of binary data which are magnetically recorded with a magnetic recording head which may be part of a credit card embossing machine or part of other card processing apparatus, such as a graphics printer, used for printing photographic images of a card holder etc. on the card. The United States and Japan have set standards for recording the magnetic stripes of credit cards. The American standard is known as the ANSI X4.16-1983 which is a revision of ANSI X4.16-1976 and ANSI X4.16A-1977. This standard sets a basic density of 210 bits per inch on the magnetic stripe of a credit card to be used for financial services which has three tracks of data. Similarly, the Japanese standard, known as NTT, also specifies 210 bits per inch of binary data encoded on the magnetic stripe of a credit card.
It is necessary for a credit card embosser or other mechanism which records the tracks of data on credit cards to have the magnetic recording head adjusted within an alignment specification from a true normal to the longitudinal axis of the magnetic recording medium. The United States Standard is .+-.20 minutes and the Japanese Standard is .+-.10 minutes which hereinafter are referred to as the "specification" or the "alignment specification". Alignment within this specification is necessary to produce an acceptable recording level of the tracks of data on the magnetic recording medium of the credit card to facilitate reading by magnetic card readers used commonly today with financial transactions. The solid line in FIG. 1 is the true normal desired orientation and the dotted line represents a misalignment of the longitudinal axis of the magnetic head (not illustrated) recording the binary data from the desired true normal. The present invention pertains to the adjustment of the longitudinal axis of the magnetic head from a misalignment represented by the dotted line to be as close as possible to the true normal represented by the solid line.
The current method of adjustment of the alignment of the magnetic head in a recording system for magnetic stripes of credit card embossing machines is very tedious. The adjustment entails the previously described orientation of the longitudinal axis of the magnetic head to the solid line orientation of FIG. 1. The Assignee aligns the magnetic recording heads of credit card embossers by loosening or tightening screws as described below which move the longitudinal axis of the head relative to a normal to the longitudinal axis along which the magnetic stripe of a credit card travels and to the longitudinal axis of the magnetic stripe being recorded by the magnetic recording head of the credit card embosser. The Assignee's method of adjusting head skew involves making a recording with the standard bit density of 210 bits per inch on a credit card blank followed by making the magnetic bits visible with an iron powder developer. Thereafter, measurement of the complement of the angle illustrated in FIG. 1 is made.
FIGS. 2 and 3 illustrate the head mounting mechanism of the Assignee's Advantage credit card embosser. As illustrated therein, a magnetic head 12 for recording three tracks is mounted in a support block 14. The support block has a slot 16 which extends almost completely across its width, permitting the portion of the support block on which the magnetic head is mounted to be rotated causing the longitudinal axis of FIG. 1 as identified by the dotted line to move toward or away from the true normal identified by the solid line by the tightening or loosening of screws 18 and 20. The tightening or loosening of the screws 18 and 20 permits the angular adjustment through a number of minutes to bring the alignment angle within the specification of alignment to the true normal identified by the solid line.
This measurement is made with a toolmaker's microscope which is used to read the complement of the angle of FIG. 1 to determine how many minutes of angle the longitudinal axis is out of specification from the true normal. When the angle is outside of the specification, the position of the head is adjusted by tightening or loosening the screws 18 and 20 to attempt to bring it within specification. Thereafter, a card is again recorded, developed with iron powder and the complement of the angle of FIG. 1 is again measured until proper adjustments have been made to bring the head into the specification. This is a trial and error method which is time consuming and does not readily produce accurate adjustments. As a consequence, the alignment of the head in a credit card embossing machine prior to shipment to a customer is an expensive process which is not done with the highest precision.
An out of specification alignment of a magnetic head in an embosser or other credit card processing apparatus which records the magnetic stripe can cause magnetically encoded credit cards to be rejected because of poor signal response of the magnetic head due to misalignment. During embossing of credit cards, the magnetic stripe is recorded and then read to verify the correctness of the recorded data. Credit card embossers, such as the Assignee's Advantage, monitor the output signal from the magnetic head in reading the previously recorded digital data. A variable level threshold detector of the embosser is set at the factory to a level to reject cards which produce a playback signal of the digital data below the threshold which rejects recorded cards having recording or magnetic stripe defects.
Furthermore, there is a need to permit the actual customer who receives the embossing or other credit card processing machine to, from time-to-time, measure the alignment of the magnetic recording head to determine if it is within the specification as set at the factory. There is no current methodology which permits this to be done other than to duplicate the process described above which is performed by the manufacturer which is not acceptable for customers because of the specialized equipment and expertise required to perform the process.